Rotational Cipher in Python

Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.

Rotational Cipher

Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.

The Caesar cipher is a simple shift cipher that relies on
transposing all the letters in the alphabet using an integer key
between 0 and 26. Using a key of 0 or 26 will always yield
the same output due to modular arithmetic. The letter is shifted
for as many values as the value of the key.

The general notation for rotational ciphers is ROT + <key>.
The most commonly used rotational cipher is ROT13.